The present invention relates to vehicle seat belt retractors of the type that have a tension-reduction mechanism. Belt retractors of this type are known in the art and solve the problem common to retractors without tension-elimination or tension-reduction features of providing either no tension or low tension when the belt is fitted to the vehicle occupant, thus making the belt more comfortable and still imparting sufficient winding force to the belt reel to retract the belt.
Retractors having tension-relief mechanisms are described and shown, for example, in U.S. Pat. No. 4,494,709 and British Pat. No. 2,072,490. The tension-reduction mechanisms of the retractors of those patents employ two winding springs connected in series with each other between the retractor frame and the belt reel. A gear clutch mechanism interposed between the two springs, one disc element of which is arranged to be fixed to the frame when the belt is in use, enables one winding spring to be deactivated while the other winding spring allows the belt to be pulled out when the occupant leans forward and then restores the belt to a memorized, tensionless state.
While the retractors of the aforementioned patents have desirable features and are reliable, they are relatively complicated, which means they are expensive to make, increase the size of the retractor, and are subject to malfunctions of the relatively complicated tension-relief mechanism.